¿how can I extract let's say frame 100 from my clip?

¿anyone a suggestion?

thanks in advance

View the clip in preview monitor, calculate mm:ss:pp for the target frame, stop the clip at that frame, right click and "save current frame" (or similar).

you can use gnome-mplayer as an easy gui for seeking and capturing frames -deinterlaced too -but compare Q with kdenlive?

Or, what I find is easiest, is to just toggle "hh mm.ss" to "Frames" in the bottom right corner of Kdenlive and then drag the monitor pointer along until it reaches your desired frame.